Heating-furnace



C. L. W. THINKS.

HEATING FURNACE.

APPLICATION HLED AUG.28,1919.

1,342,074, Patented June 1, 1920.

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3; 2H1: L 5- L t O l 1 E H l'lu nior WLbIBSS W W flfW -dM L. W. TRINKS.

HEATING FURNACE.

APPLICATION FILED Aue.2e. I919.

Patented Jun 1, 1920.

3 SHEETSSHEET 2.

C. L. W. THIN-KS. HEATING FURNACE. APPLICATION FILED AUG.28. 1919.

1,342,074. Patented June 1, 1920.

3 SHEETS-SHEET 3.

"NIHI'HIWVITIIUHI I Mentor ed, M

. to the accompanying drawings, forming- UNITED STATES PATENT OFFICE.

CHARLES L. w. TRINKs, or PITTSBURGH, PENNSYLVANIA, AssIGNoR To TATE-JONES & COMPANY, INC., on PITTSBURGH, PENNSYLVANIA, A CORPORATION or PENN- SYLVANIA.

\. HEATING-FURNACE.

TRINKS, residing atPittsburgh, Allegheny county, Pennsylvania, have invented a new and useful Improvement in Heating-Furnaces, of which the following is a full, clear, and exact description,referencebeing had part of this specification, in which Figure l is a front elevation of a furnace embodying my invention;

Fig. 2 vis a transverse vertical section, taken on the line II-II of Fig. 3';

Fig. 3 is a horizontal section taken on th line IIIIII of Fig. 2;

Fig. 4 is a vertical section taken on the line IV;-IV of Fig. 1;

Figs. 5 to 8 are detail views of the various plates constituting the inner casing; Figs. 5 and 8 illustrating the bottom and top plate, respectively, while Figs. 6 and 7 illustrate the end plates.

My invention relates to heating furnaces, such as are used in forging practice. These furnaces, as heretofore constructed, are both uneconomical and troublesome in their operation. They are uneconomical because the maintaining of a high furnace temperature therein causes the fluid gases to leave at high temperatures so that only a very small part of the heat of combustion is utilized. They .are also uneconomical because the walls must be comparatively thin, which means great heat losses by radiation. It is necessary to construct furnaces with thin walls because otherwise the refractories would become overheated on the inside and would not stand up for any length of time. These furnaces are troublesome, because even with the comparatively thin walls of which they are constructed, the heat distortion of the refractories causes the walls to buckle and the roofs to cave in. This requires frequent rebuilding of the furnaces.

My invention is designed to overcome these difficulties and to provide a furnace of this character in which the walls are so con- 'structed as to withstand high temperatures metallic casing 6.

Specification of Letters Patent. Patented J 1 1.920 Application filed August 28, 1919. Serial No. 320,504. I

ferred embodiment thereof and which will now be described, it beingpremised, however, that various changes can be made in the details of construction, combination and arrangement of the various parts, without departing from the spirit and scope of my invention, as defined in the appended claims.

In these drawings, the numeral 1 designates the heating chamber of the furnace which is immediately surrounded by thin refractory walls 2. These are, in turn, inclosed in a metallic casing 3, outside of which is a surrounding air space 4, adapted to carry air for combustion in the furnace 111 2). continuous path practically entirely around the furnace. The air space 4: is surrounded by a heat-insulating material 5, and this in turn is inclosed in an air-tight I am aware it is not new to provide a furnace having a double wall with an air circulating space therein for the purpose of preheating air. Such furnace, however, as

heretofore built, has been a failure because it is impossible to keep the refractories from cracking and leaking and the maintenance cost was so excessive that the furnaces had to be abandoned. I overcome these difficulties by providing two metallic casings 3 and 6. The inner casing 3 will, of course, become heated to a relatively high temperature. In fact, it may assume a dull red heat,

For that reason, I use for this casing a material such as cast iron which will not readily oxidize. The outer casing willremain comparatively cold so that a very light steel shell will sufiice. The inner shell or casing serves a double purpose. First, its strength and rigidity acts to hold the refractory walls 2 in place, keeping them from cracking and caving in; and second, it prevents leakage of combustion air into the furnaces or places where such air is not wanted. The flow of the combustion air around the furnace should preferably reach all wallsurfaces of the air space 4, so as to leave no dead or uncooled areas. The air may be caused to take various paths. In the arrangement shown, the air enters through the bottom connection 7, as indicated by the arrows, and thence flowsinto the air space at the right hand end of the furnace. Here the flow divides, part of the air passing upwardly through the top space and thence downwardly into the space at the front side I o the furnace; and part flowinglaterally with a heating chamber 11 which is arranged constituting the casing 3 may be provided 1 with suitable slots, as indicated at 8.

lates constitut- Ipreferably provide the hese IlbS serve .-the shell 3 with ribs9.

a ouble purpose; firstthey direct the flow of air so v as to leave no dead spaces; and

'.second,ithey serve as abutments for the insuing material 5, holding the latter the "er distance from the shell oricaslng 3. ribs 9fare .arranged to extend in the (general direction of the desired air flow.

In forge furnaces without a door such as I have illustrated, I preferably .provide for the further preheating of the combustion .air, as follows: i

' A suitable duct or flue 10 connects the air space 4 at the left hand end-of the furnace at the front side of the furnace above the door. From this chamber 11 it passes by a flue or duct 12 to the burner 13. The chamber 11 receives heat from two sources, viz: from the interior of the furnace and through the thin inner'wall 2 and also from the flame and hot gases which pass out of the door 14 and upwardly through the chimney 15. To increase the heat absorption from the flame, the front wall of this chamber is provided with a plurality of ribs 16. which are directly exposed to the flame and hot gases. andform an extended heat absorbing area. The inner wall of this chamber also has ribs which are indicated at 17 for the purpose of increasing its heat transmitting area to i the combustion. air passing through said chamber. This chamber 11 is made of some suitable'heat resisting materialsuch as cast iron or nichrome.

The advantages of my invention Wlll be I readily-understood bythose. familiar with furnaces of this class since I provide a long life thin-walled furnace in which the heat transmitted through the walls, and usually lost, is returned'to the furnace to a large degree. My invention also provides a furnace in which the metallic shells not only act to hold the refractory and heat-insulating material in place in service; but they also hold such parts during shipment and handling of the furnace, this largely preventing breakage of the refractories during such shipment metalcasing surrounding said walls, an air circulating space around the metal casing, heat-insulating material outside of said air space, and a metalllc cas ng surround ng the heat-insulating material, substantiallyhs described.

2; A high temperature heating furnace whose walls comprise an inner refractory material, :inner and outer metal casings, an air space lntermediate' said casing, and a heat insulator outside of the'a1r space,'substantially as described.

together. with means for circulating air for combustion therethrough, substantially as described.-

5. heating furnace having inner and outer metallic casings, and an air duct surrounding the furnace chamber between said casings, the furnace havinga door and an .air chamber in the furnace wall above said door, and circulating connections leading from the air space around the furnace to said chamber, and from said chamber to the burner of the furnace, substantially as described.

6. A heating furnace having thin refrac-, I

tory Walls, a metal casing around the refractory walls, an air space around said metal casing in the botto1n, s1de and roof Walls, an air-preheating chamber in .the

furnace wall above the furnace door, and aircirculat'mg connections leading from the air spaces in the walls to said chamber and from the preheating chamber to the furnace, substantially as described. I

7. A heating furnace having thin refractory walls, a metal casing surrounding said walls and having spacing-ribs on its outer surface, said spacing ribs beingarranged to direct the flow of air along said casing, a heat-insulating material resting against said ribs, and an outer metal casing surrounding the heat-insulating material, substantially as described. r

8. A heating furnace-having a preheating chamber around its-wallabove its door, said chamber being provided with external ribs extending into the path of the flame issuing from the furnace door and also having internal ribs extending in the direction of the flow of air through the chamber, substantially as described.

9. A heating furnace having an open door and a chimney extending upwardly from theouter side of the. door, an air-preheating chamber having ribs extending outwardly 1 into the chimney, and other ribs extending inwardly across said chamber, substantially as described.

In testimony whereof I have hereunto set 

